To use this application, you only have to start it and wait for it to find all of the available networks in the area, although some times this can take a long time depending on the number of nearby broadcasting networks.
Once this process is complete, you can select your network (it is important not to try this on outside networks, as this is a prosecutable offence), and check its security. If you can see the password, it might be a good idea to think about changing it because it means that any user can enter you network.
Wifi Hacker ULTIMATE Wifi is a tool that should not be used without a certain knowledge of networks, because although it is easy to use and can help you secure your own connections, the consequences of improper use can be quite severe. So its like they say, "Use at your own risk."